Governing and synchronizing system



June 24, 1941. HERZQG 2,246,516

GOVERNING AND SYNCHRONIZING SYSTEM Filed March 13, 1939 2 Sheets-Sheet l&

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By ZZ; 7

June 24, 1941.

E. HERZOG 2,246,516

GOVERNING AND SYNCHRONIZING SYSTEM Filed March 13, 1959 2 Sheets-Sheet 2EUGENE HIE 13 22 6 Patented June 24, 1941 GOVERNING AND SYNCHRONIZINGSYSTEM Eugene Herzog, Dayton, Ohio Application March 13, 1939, SerialNo. 261,541

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 7 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to a governing system which holds the speed ofone or more prime movers or motors fixed in relation to certain fixed oradjustable electrical quantities used as standards.

It is an an object of the invention to provide a light weight standardand one of low energy consumption for the speed control of rotatingapparatus.

'It is a further object of the invention to provide a non-rotatingstandard for the speed control of rotating apparatus.

It is a still further object to provide a means of speed control whichprovides greater accuracy as to the speed desired at a lower cost.

It is a still further object to provide a means of speed control for aplurality of rotating equipment whereby the speed of each rotatingequipment is held in fixed relation to a speed reference by controllingan electrical effect of each in relation to a standard electricalquantity.

Other objects and advantages will become apparent as the invention isdescribed.

Fig. 1 is a, schematic view showing one embodiment of my invention, inwhich the frequency effect produced by the engine speed is compared to astandard or reference frequency, the difference in frequency betweenthereference frequency and the engine-produced frequency being utilized tocontrol the speed of the engine;

Fig. 1A is an elevational view showing the details of a control switchemployed in the various modifications of my invention:

Fig. 2 is a view similar to Fig. 1, in which the voltage differencebetween a voltage produced in accordance with the speed of the engineand the voltage of a battery or other reference means is utilized tocontrol the speed of the engine; and

Fig. 3 is a view similar to Figs. 1 and 2, showing the utilization ofcurrent difference effects between a standard or reference current and acurrent produced in accordance with the speed of the engine for purposesof controlling the speed of the engine.

In the various embodiments illustrated herein similar parts will bedesignated by the same reference characters.

While the invention is described in particular in its application to thegoverning and synchronizing of airplane engines it is not restricted tosuch an application but may be used in the governing and synchronizingof any other kind of prime movers or motors where the speed may becontrolled by increasing and decreasing either the power input, such asthe engine throttle, or the power output, such as a propeller pitchchanging means.

In accordance with one embodiment of my invention the speed of one ormore engines is controlled by comparing the electrical frequency effectproduced by suitable means directly or indirectly associated with andoperating as a function of the speed of said engine or enginesrespectively, with a standard or reference frequency and utilizing thedifference effect, if any, between said produced frequency orfrequencies and said standard frequency for controlling suitablevariable pitch propeller means associated with said engine or enginesand thereby control the speed or speeds thereof. This embodiment of myinvention is illustrated in Figure 1, in which I have shown two aircraftengines ill the output of each of which is governed by varying the pitchof a propeller l2 through suitable propeller pitch changing means I ofthe well-known electric motor type described in Patent No. 1,951,320granted on March 13, 1934. For obtaining the particular electricalreference quantity, i. e. the reference frequency, current is suppliedfrom a battery It to a direct current motor 18 which is designed to runat a constant but adjustable speed. The speed adjustment is obtained bymeans of a rheostat 20 as is well known in the electrical art. Thedirect current motor I! drives mechanically through a shaft 22 analternating current polyphase generator 24 which in consequence runs ata constant but adjustable speed and its electrical output is at aconstant but adjustable reference frequency. This electrical output isimpressed by means of conductors 26 on the stator 28 of wound rotorinduction motors 30 of the slip ring type the rotors 32 of which aredriven by the engines M respectively at speeds proportional to thecorresponding engine speeds through suitable mechanical connections,such as cam shaft drive (not shown). Under these conditions a voltagewill appear at the slip rings 34 of each of the wound rotor inductionmotors 30 which voltage is proportional in magnitude and frequency tothe difference in speed between each of the engines and the masteralternator 24 and whose phase rotation respectively is dependent onwhether the engine or the rotating magnetic field due to the masteralternator has the greater speed. I

The electrical output of each of the slip ring induction motors ispreferably utilized to actuate creasing torque in motor 50. It

standard reference voltage.

a corresponding relay means which in turn controls the pitch varyingmeans of the propelie As illustrated a three-phase motor 38 iselectrically connected by means of conductors 38 and brushes to the sliprings 8!. so that the out- I with, a contact arm 44 which closes thepitch changing motors circuit 45 through contact points 46 or 48, thatare symmetrically disposed with relation to the arm 44 in the neutral ormid position thereof, i. e. where the speed of the englue and the speedof the master alternator are in synchronism, the details of the switchfor controlling the pitch-changing motor being illustrated in Fig. 1A.In this neutral position the contact arm 44 is out of contact with thecontacts 56 or 68. These contact points are electrically connected tothe reversible electric motor 50 of the pitch changing means in such amanner that the torque of the motor will increase in proportion to thedeflection of the arm 44 in either direction. As illustrated motor 50 isof the split field series wound type and is connected with a source ofenergy 52 in series with either set of resistors 54 or 56 by means ofthe contact points 46 or 48 respectively and contact arm 48. As thecontact arm id deflects in one direction or the other making contactwith either contacts 46 or 68' the resistance in the motor circuit willbe progressively diminished producing a progressively inwill thus beseen that the torque available for correction will depend on the extentof off speed of each of the engines relative to the master alternator orreference.

The torque motor 36 here simply acts as a relay preserving theproportionality between error and adjustment of speed of the engines andpermitting the entire system to be built of light weight because of thesmall power required to actuate the relay. It will be understood thatwhere weight is not an important factor the output of the slip ringmotor 30 may be made large enough to operate directly the conventionalspeed adjusting device such as the propeller pitch change motor or valvefor hydraulic control or the throttle control.

The above system of frequency balancing is a preferred method because ofits simplicity and because of the ease with which proportionaladjustment is attained but this invention is not to be restricted to theparticular means of creating or matching the standard frequency or tothe devices illustrated utilizing the frequency difference for speedcontrol as other equivalent devices may be utilized for these purposes.

My invention further contemplates controlling the speed of the engine bycomparing the voltage produced by the engine driven generator with aThis'variation is illustrated in Figure 2 wherein each of the enginesill to be controlled drive a generator 58 that produces a voltageproportional to the engine speed. The electrical circuit foraccomplishing the control for each engine consists of the assure throughthe relay 66, one coil 63 of the relay being connected across thegenerator 58, and the other, 63 being connected across the battery 60,both of the coils 63 being connected in parallel with the battery. Allthe magneto motive force developed in one 01' the coils of the rotor ofdifferential relay BE-Which includes the polarizing magnet 6'Iby thegenerator 58, is opposed by.

the magneto motive force developed in the other rotor coil of thedifierential relay 66 by the battery 6b. The voltmeter 54 serves toindicate the desired setting of the potentiometer 62. As long as thegenerator 58 is driven at the desired speed, the rotor of thediiferential relay 66 will remain in a neutral position at right anglesto the plane of the field of the polarizing magnet used in differentialrelays of the type described. The source 60, while illustrated as abattery, may be a generator that constitutes the source of the standardor reference voltage. This reference voltage is adjusted to the desiredvalue by a potentiometer B2 to allow for any variations of the source orto obtain an adjustment for the speed desired. The particular speed towhich the source is adjusted is indicated by the voltmeter 64 which maybe calibrated in terms of engine speed to aid the pilot or operator.Generator 58 produces a voltage proportional to the engine speed. Asuitable voltage difierential relay 66 of well-known construction suchas a dArsonval type instrument is commonly coupled to the output of thegenerator 58 and the reference source 60, the movable por-' tion of thisinstrument is connected by a shaft 65 to the contact arm 44 that isactuated in one direction or the other by a difierence in voltagebetween the voltage produced by the generator and that produced by thesource of. standard voltage, the sign of the voltage difierencedepending on whether the voltage produced by the generator is greater orless than that of the source.

Movement of the contact arm 44 in the clockwise or counterclockwisedirection will close the circuit d5 through contacts 46 or 48respectively, causin the motor 50 to operate in one direection or theother and with a torque corresponding to the extent of variation ofresistance of the circuit due to the deflection of the contact arm. Theservomotor 50 is controlled, by means of the relay 66 through the arm G4and contact points 46, 48 in the manner described above in connectionwith Fig. 1.

Fig. 3 illustrates a still further variation of my invention in whichprovision is made for controlling speed by means of comparing currentquantities. The engines in whose speed is to be controlled respectivelydrive through suitable mechanical connection generators 58. Control isobtained by comparing the current in a reference circuit consisting of asource 60, an adjustable rheostat 68, an ammeter 16, and a pair of coils10 connected in series, with the variable currents in circuits it, eachconsisting of a generator 58 and a coil i2. The source 60 which may be abattery or generator supplies the reference current which is adjusted bymeans of the rheostat 68 to a standard value. The rheostat 68 providesadjustment for variations in the source and for variations in the speeddesired. The standard current and in consequence the standard speed isindicated by the ammeter 1B which is calibrated in terms of speed toindicate the set speed to the pilot or operator. Each generator circuithas a resistance such that for all reference current settings thegenerator 58 will produce current values that are proportional to thereference current and as illustrated the controlled current for alldifferent settings will be equal to the reference current when the speedof the engine is at the set value. The controlled current and thereference current are compared by a current differential relay 18, suchas a d'Arsonval type instrument, which includes the two windings l and12. A contact arm 44 is actuated by the current differential relay dueto a current difference between the reference current and the controlledcurrent, the magnitude of its deflection depending on the extent of thecurrent difference, the direction of its deflection depending uponwhether the current produced by the generator is greator or less thanthat produced by the reference source. Deflection of the contact arm inthe clockwise direction will close the motor circuit 45 causing themotor 50 to operate in one direction and deflection of the contact armin the counterclockwise direction will cause rotation in the oppositedirection, the torque of the motor corresponding to the extent of thedeflection of the contact arm.

In the various embodiments of my invention the speed is controlled bymeans of differences of frequency, voltage or current. The control ineach case may be accomplished either by producing a mechanical effectsuch as torque proportional to such electrical quantities and thenactuating the speed control by the torque difference either directly orthrough intermediate relays and servo mechanisms. It will be understoodhowever that the standard and controlled quantities may be compareddirectly, their difference produced and then converted into mechanicalcontrol effects. Whether one method or the other is used will depend onvarious factors. Direct comparison is more sensitive but may produceundesirable mutual effects if two or more engines are controlled at thesame time: comparison after conversion to mechanical effects usuallypermits a better control of these mutual effects between engines.

Where two or more engines are controlled by electrical meanselectrically coupled to a reference electrical circuit, the change inthe s eed of one of the engines will produce a mutual effect in theelectrical circuits associated with the other enginesv This mutualinterference is a function of the electrical couplin between the esective ci cuits and with the system illustrated in Fig. 3. where thecircuits are coupled inducely and where direct cu rents are compared,then the mutual effects will be restricted to transsient conditions andthe mutual interference will be largely eliminated or reduced to theminimum. The circuits illustrated above can be designed to provide aminimum-optimum coupling, 1. e. the coupling should be such as to allowthe minimum transfer of energy from one circuit to the other especiallyfrom one controlled circuit to another controlled circuit. The practicallimita- -tion on the increasing looseness of coupling is the decreasingsensitivity of the control beyond a certain point. The balance betweencontrol of mutual effects and sensitivity has to be adapted for eachparticular use.

.The advantages set forth for loose coupling relation between thecontrolled and reference circuits where current quantities are utilizedas a reference medium is equally advantageous where the reference mediumis an electrical frequency or an electrical voltage.

It is to be understood that the above described embodiments of myinvention are for the purpose of illustration only, and various changesmay be made thertin without departing from the spirit or scope of theinvention.

What I claim as new and Letters Patent is:

l. A synchronizing system for a plurality of prime movers comprisingmeans for producing an electrical reference quantity, meansassociatedwith and actuated byeach of said prime movers for producingvariable electrical quantities similar to and comparable with saidreference quantity and proportional in value to the speeds of said primemovers, respectively, means associated with said reference quantityproducing means and each of said variable quantity producing means forproducing a corresponding number of difference effects, and separatemeans responsive to said difference effects for controlling the speedsof said prime movers, said separate means includdesire to secure by ingcontrol elements for varying the respective speeds of said prime movers,electric servomotors operatively associated with said control elementsfor positioning the same to control the prime mover speeds, and meansresponsive to said difference effects for controlling the supply fenergy to said servomotors So that the respective speeds thereof areproportional to the instantaneous magnitudes of said difference effectsrespectively.

2. An electrical control system for controlling the speed of a primemover comprising an electrical circuit for producing an electricalreference quantity, an electric generating circuit associated with saidprime mover for producing a variable electrical quantity similar to andcomparable with said reference quantity and proportional to the speed ofsaid prime mover, said circuits being loosely coupled and having meansassociated with said coupling for producing difference quantity effects,and means for utilizing said difference effects to control the speed ofsaid prime mover and in proportion to the instantaneous magnitude ofsaid difference effects.

3. An electrical control system for regulating the speed of a primemover comprising means for producing an electrical reference voltage ofpredetermined value, prime mover actuated means for producing a variableelectrical voltage comparable with said reference voltage andproportional in value to the speed of said prime mover, means forproducing a difference efiect between said reference voltage and saidvariable voltage, and means responsive to said difference effect forvarying the speed of said prime mover in proportion to the instantaneousmagnitude of said difference eflect.

4. A synchronizing system for a plurality of prime movers comprisingmeans for producing an electrical reference voltage, means associatedwith and actuated by each of said prime movers for producing variableelectrical voltages comparable with said reference voltage andproportional in value to the speeds of said prime movers, respectively,means associated with said reference voltage producing means and each ofsaid variable voltage producing means for producing a correspondingnumber or diii'erence eflects, and separate means responsive to saiddifference eiiects for controlling the speeds of said prime movers inproportion to the instantaneous magnitudes of said difierence efiectsrespectively.

5. An electrical control system for regulating the speed of a primemover comprising means for producing an electrical reference current ofadjusted predetermined value, prime mover actuated means for producing avariable electrical current comparable with said reference current andproportional in value to the speed of said prime mover, means forproducing a. difference efiect between said reference current and saidvariable current, and means responsive to said difl'erence efiect iorvarying the speed of said prime mover in proportion to the instantaneousmagnitude of said difference eflect.

6. An synchronizing system for a plurality of prime movers comprisingmeans for producing an electrical reference current, means associatedwith and actuated by each of said prime movers for producing yariableelectrical currents comparable with said reference current andproportional in value to the speeds of said prime movers, respectively,means associated with said reference current producing means and each ofsaid varing two electrical circuits, one of said circuits ineluding inseries relation a battery constituting a source of current supply, arheostat ior adjusting said current supply to obtain a referencecurrent, an ammeter calibrated in terms of speed for indicating thereference current value, and a coil, theother said circuits including inseries relation a-prime mover driven generator and a coil, said circuitsbeing so constructed and arranged that the currents flow in oppositesenses therethrou'gh to thereby produce opposite magnetic fields, andmeans associated with said coils and movable in opposite directions inresponse to the diflerences insald magnetic efiects, and meanscontrolled by said difierential responsive means for regulating themovement of the prime mover control part in proportion to theinstantaneous deflection oi the differential responsive means.

EUGENE rmazoo.

